Merge pull request #2497 from karalabe/version-contract-3

Geth release oracle

accounts/abi/bind/backend.go

@@ -47,7 +47,8 @@ type ContractCaller interface {
 // used when the user does not provide some needed values, but rather leaves it up
 // to the transactor to decide.
 type ContractTransactor interface {
-	// Nonce retrieves the current pending nonce associated with an account.
+	// PendingAccountNonce retrieves the current pending nonce associated with an
+	// account.
 	PendingAccountNonce(account common.Address) (uint64, error)
 
 	// SuggestGasPrice retrieves the currently suggested gas price to allow a timely
@@ -62,7 +63,7 @@ type ContractTransactor interface {
 	EstimateGasLimit(sender common.Address, contract *common.Address, value *big.Int, data []byte) (*big.Int, error)
 
 	// SendTransaction injects the transaction into the pending pool for execution.
-	SendTransaction(*types.Transaction) error
+	SendTransaction(tx *types.Transaction) error
 }
 
 // ContractBackend defines the methods needed to allow operating with contract

cmd/geth/main.go

@@ -18,6 +18,7 @@
 package main
 
 import (
+	"encoding/hex"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -41,31 +42,48 @@ import (
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/node"
 	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/release"
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
 const (
-	ClientIdentifier = "Geth"
-	Version          = "1.5.0-unstable"
-	VersionMajor     = 1
-	VersionMinor     = 5
-	VersionPatch     = 0
+	clientIdentifier = "Geth"     // Client identifier to advertise over the network
+	versionMajor     = 1          // Major version component of the current release
+	versionMinor     = 5          // Minor version component of the current release
+	versionPatch     = 0          // Patch version component of the current release
+	versionMeta      = "unstable" // Version metadata to append to the version string
+
+	versionOracle = "0xfa7b9770ca4cb04296cac84f37736d4041251cdf" // Ethereum address of the Geth release oracle
 )
 
 var (
-	gitCommit       string // set via linker flagg
-	nodeNameVersion string
-	app             *cli.App
+	gitCommit string         // Git SHA1 commit hash of the release (set via linker flags)
+	verString string         // Combined textual representation of all the version components
+	relConfig release.Config // Structured version information and release oracle config
+	app       *cli.App
 )
 
 func init() {
-	if gitCommit == "" {
-		nodeNameVersion = Version
-	} else {
-		nodeNameVersion = Version + "-" + gitCommit[:8]
+	// Construct the textual version string from the individual components
+	verString = fmt.Sprintf("%d.%d.%d", versionMajor, versionMinor, versionPatch)
+	if versionMeta != "" {
+		verString += "-" + versionMeta
+	}
+	if gitCommit != "" {
+		verString += "-" + gitCommit[:8]
 	}
+	// Construct the version release oracle configuration
+	relConfig.Oracle = common.HexToAddress(versionOracle)
 
-	app = utils.NewApp(Version, "the go-ethereum command line interface")
+	relConfig.Major = uint32(versionMajor)
+	relConfig.Minor = uint32(versionMinor)
+	relConfig.Patch = uint32(versionPatch)
+
+	commit, _ := hex.DecodeString(gitCommit)
+	copy(relConfig.Commit[:], commit)
+
+	// Initialize the CLI app and start Geth
+	app = utils.NewApp(verString, "the go-ethereum command line interface")
 	app.Action = geth
 	app.HideVersion = true // we have a command to print the version
 	app.Commands = []cli.Command{
@@ -257,7 +275,7 @@ func makeDefaultExtra() []byte {
 		Name      string
 		GoVersion string
 		Os        string
-	}{uint(VersionMajor<<16 | VersionMinor<<8 | VersionPatch), ClientIdentifier, runtime.Version(), runtime.GOOS}
+	}{uint(versionMajor<<16 | versionMinor<<8 | versionPatch), clientIdentifier, runtime.Version(), runtime.GOOS}
 	extra, err := rlp.EncodeToBytes(clientInfo)
 	if err != nil {
 		glog.V(logger.Warn).Infoln("error setting canonical miner information:", err)
@@ -275,7 +293,7 @@ func makeDefaultExtra() []byte {
 // It creates a default node based on the command line arguments and runs it in
 // blocking mode, waiting for it to be shut down.
 func geth(ctx *cli.Context) {
-	node := utils.MakeSystemNode(ClientIdentifier, nodeNameVersion, makeDefaultExtra(), ctx)
+	node := utils.MakeSystemNode(clientIdentifier, verString, relConfig, makeDefaultExtra(), ctx)
 	startNode(ctx, node)
 	node.Wait()
 }
@@ -339,7 +357,7 @@ func initGenesis(ctx *cli.Context) {
 // same time.
 func console(ctx *cli.Context) {
 	// Create and start the node based on the CLI flags
-	node := utils.MakeSystemNode(ClientIdentifier, nodeNameVersion, makeDefaultExtra(), ctx)
+	node := utils.MakeSystemNode(clientIdentifier, verString, relConfig, makeDefaultExtra(), ctx)
 	startNode(ctx, node)
 
 	// Attach to the newly started node, and either execute script or become interactive
@@ -372,7 +390,7 @@ func console(ctx *cli.Context) {
 // of the JavaScript files specified as command arguments.
 func execScripts(ctx *cli.Context) {
 	// Create and start the node based on the CLI flags
-	node := utils.MakeSystemNode(ClientIdentifier, nodeNameVersion, makeDefaultExtra(), ctx)
+	node := utils.MakeSystemNode(clientIdentifier, verString, relConfig, makeDefaultExtra(), ctx)
 	startNode(ctx, node)
 	defer node.Stop()
 
@@ -488,11 +506,8 @@ func gpubench(ctx *cli.Context) {
 }
 
 func version(c *cli.Context) {
-	fmt.Println(ClientIdentifier)
-	fmt.Println("Version:", Version)
-	if gitCommit != "" {
-		fmt.Println("Git Commit:", gitCommit)
-	}
+	fmt.Println(clientIdentifier)
+	fmt.Println("Version:", version)
 	fmt.Println("Protocol Versions:", eth.ProtocolVersions)
 	fmt.Println("Network Id:", c.GlobalInt(utils.NetworkIdFlag.Name))
 	fmt.Println("Go Version:", runtime.Version())

cmd/utils/flags.go

@@ -48,6 +48,7 @@ import (
 	"github.com/ethereum/go-ethereum/p2p/nat"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/pow"
+	"github.com/ethereum/go-ethereum/release"
 	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/ethereum/go-ethereum/whisper"
 )
@@ -641,7 +642,7 @@ func MakePasswordList(ctx *cli.Context) []string {
 
 // MakeSystemNode sets up a local node, configures the services to launch and
 // assembles the P2P protocol stack.
-func MakeSystemNode(name, version string, extra []byte, ctx *cli.Context) *node.Node {
+func MakeSystemNode(name, version string, relconf release.Config, extra []byte, ctx *cli.Context) *node.Node {
 	// Avoid conflicting network flags
 	networks, netFlags := 0, []cli.BoolFlag{DevModeFlag, TestNetFlag, OlympicFlag}
 	for _, flag := range netFlags {
@@ -772,7 +773,11 @@ func MakeSystemNode(name, version string, extra []byte, ctx *cli.Context) *node.
 			Fatalf("Failed to register the Whisper service: %v", err)
 		}
 	}
-
+	if err := stack.Register(func(ctx *node.ServiceContext) (node.Service, error) {
+		return release.NewReleaseService(ctx, relconf)
+	}); err != nil {
+		Fatalf("Failed to register the Geth release oracle service: %v", err)
+	}
 	return stack
 }
 

eth/api.go

@@ -52,14 +52,14 @@ import (
 	"golang.org/x/net/context"
 )
 
-// ErrNoCode is returned by call and transact operations for which the requested
+// errNoCode is returned by call and transact operations for which the requested
 // recipient contract to operate on does not exist in the state db or does not
 // have any code associated with it (i.e. suicided).
 //
 // Please note, this error string is part of the RPC API and is expected by the
 // native contract bindings to signal this particular error. Do not change this
 // as it will break all dependent code!
-var ErrNoCode = errors.New("no contract code at given address")
+var errNoCode = errors.New("no contract code at given address")
 
 const defaultGas = uint64(90000)
 
@@ -107,8 +107,11 @@ type PublicEthereumAPI struct {
 }
 
 // NewPublicEthereumAPI creates a new Ethereum protocol API.
-func NewPublicEthereumAPI(e *Ethereum, gpo *GasPriceOracle) *PublicEthereumAPI {
-	return &PublicEthereumAPI{e, gpo}
+func NewPublicEthereumAPI(e *Ethereum) *PublicEthereumAPI {
+	return &PublicEthereumAPI{
+		e:   e,
+		gpo: e.gpo,
+	}
 }
 
 // GasPrice returns a suggestion for a gas price.
@@ -717,7 +720,7 @@ func (s *PublicBlockChainAPI) doCall(args CallArgs, blockNr rpc.BlockNumber) (st
 	// If there's no code to interact with, respond with an appropriate error
 	if args.To != nil {
 		if code := stateDb.GetCode(*args.To); len(code) == 0 {
-			return "0x", nil, ErrNoCode
+			return "0x", nil, errNoCode
 		}
 	}
 	// Retrieve the account state object to interact with
@@ -914,18 +917,17 @@ type PublicTransactionPoolAPI struct {
 }
 
 // NewPublicTransactionPoolAPI creates a new RPC service with methods specific for the transaction pool.
-func NewPublicTransactionPoolAPI(e *Ethereum, gpo *GasPriceOracle) *PublicTransactionPoolAPI {
+func NewPublicTransactionPoolAPI(e *Ethereum) *PublicTransactionPoolAPI {
 	api := &PublicTransactionPoolAPI{
-		eventMux:      e.EventMux(),
-		gpo:           gpo,
-		chainDb:       e.ChainDb(),
-		bc:            e.BlockChain(),
-		am:            e.AccountManager(),
-		txPool:        e.TxPool(),
-		miner:         e.Miner(),
+		eventMux:      e.eventMux,
+		gpo:           e.gpo,
+		chainDb:       e.chainDb,
+		bc:            e.blockchain,
+		am:            e.accountManager,
+		txPool:        e.txPool,
+		miner:         e.miner,
 		pendingTxSubs: make(map[string]rpc.Subscription),
 	}
-
 	go api.subscriptionLoop()
 
 	return api

eth/backend.go

@@ -119,6 +119,7 @@ type Ethereum struct {
 	protocolManager *ProtocolManager
 	SolcPath        string
 	solc            *compiler.Solidity
+	gpo             *GasPriceOracle
 
 	GpoMinGasPrice          *big.Int
 	GpoMaxGasPrice          *big.Int
@@ -260,6 +261,8 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 		}
 		return nil, err
 	}
+	eth.gpo = NewGasPriceOracle(eth)
+
 	newPool := core.NewTxPool(eth.chainConfig, eth.EventMux(), eth.blockchain.State, eth.blockchain.GasLimit)
 	eth.txPool = newPool
 
@@ -276,34 +279,31 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 // APIs returns the collection of RPC services the ethereum package offers.
 // NOTE, some of these services probably need to be moved to somewhere else.
 func (s *Ethereum) APIs() []rpc.API {
-	// share gas price oracle in API's
-	gpo := NewGasPriceOracle(s)
-
 	return []rpc.API{
 		{
 			Namespace: "eth",
 			Version:   "1.0",
-			Service:   NewPublicEthereumAPI(s, gpo),
+			Service:   NewPublicEthereumAPI(s),
 			Public:    true,
 		}, {
 			Namespace: "eth",
 			Version:   "1.0",
-			Service:   NewPublicAccountAPI(s.AccountManager()),
+			Service:   NewPublicAccountAPI(s.accountManager),
 			Public:    true,
 		}, {
 			Namespace: "personal",
 			Version:   "1.0",
-			Service:   NewPrivateAccountAPI(s.AccountManager()),
+			Service:   NewPrivateAccountAPI(s.accountManager),
 			Public:    false,
 		}, {
 			Namespace: "eth",
 			Version:   "1.0",
-			Service:   NewPublicBlockChainAPI(s.chainConfig, s.BlockChain(), s.Miner(), s.ChainDb(), gpo, s.EventMux(), s.AccountManager()),
+			Service:   NewPublicBlockChainAPI(s.chainConfig, s.blockchain, s.miner, s.chainDb, s.gpo, s.eventMux, s.accountManager),
 			Public:    true,
 		}, {
 			Namespace: "eth",
 			Version:   "1.0",
-			Service:   NewPublicTransactionPoolAPI(s, gpo),
+			Service:   NewPublicTransactionPoolAPI(s),
 			Public:    true,
 		}, {
 			Namespace: "eth",
@@ -313,7 +313,7 @@ func (s *Ethereum) APIs() []rpc.API {
 		}, {
 			Namespace: "eth",
 			Version:   "1.0",
-			Service:   downloader.NewPublicDownloaderAPI(s.Downloader(), s.EventMux()),
+			Service:   downloader.NewPublicDownloaderAPI(s.protocolManager.downloader, s.eventMux),
 			Public:    true,
 		}, {
 			Namespace: "miner",
@@ -328,7 +328,7 @@ func (s *Ethereum) APIs() []rpc.API {
 		}, {
 			Namespace: "eth",
 			Version:   "1.0",
-			Service:   filters.NewPublicFilterAPI(s.ChainDb(), s.EventMux()),
+			Service:   filters.NewPublicFilterAPI(s.chainDb, s.eventMux),
 			Public:    true,
 		}, {
 			Namespace: "admin",
@@ -351,7 +351,7 @@ func (s *Ethereum) APIs() []rpc.API {
 		}, {
 			Namespace: "admin",
 			Version:   "1.0",
-			Service:   ethreg.NewPrivateRegistarAPI(s.chainConfig, s.BlockChain(), s.ChainDb(), s.TxPool(), s.AccountManager()),
+			Service:   ethreg.NewPrivateRegistarAPI(s.chainConfig, s.blockchain, s.chainDb, s.txPool, s.accountManager),
 		},
 	}
 }

eth/bind.go

+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package eth
+
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/rpc"
+)
+
+// ContractBackend implements bind.ContractBackend with direct calls to Ethereum
+// internals to support operating on contracts within subprotocols like eth and
+// swarm.
+//
+// Internally this backend uses the already exposed API endpoints of the Ethereum
+// object. These should be rewritten to internal Go method calls when the Go API
+// is refactored to support a clean library use.
+type ContractBackend struct {
+	eapi  *PublicEthereumAPI        // Wrapper around the Ethereum object to access metadata
+	bcapi *PublicBlockChainAPI      // Wrapper around the blockchain to access chain data
+	txapi *PublicTransactionPoolAPI // Wrapper around the transaction pool to access transaction data
+}
+
+// NewContractBackend creates a new native contract backend using an existing
+// Etheruem object.
+func NewContractBackend(eth *Ethereum) *ContractBackend {
+	return &ContractBackend{
+		eapi:  NewPublicEthereumAPI(eth),
+		bcapi: NewPublicBlockChainAPI(eth.chainConfig, eth.blockchain, eth.miner, eth.chainDb, eth.gpo, eth.eventMux, eth.accountManager),
+		txapi: NewPublicTransactionPoolAPI(eth),
+	}
+}
+
+// ContractCall implements bind.ContractCaller executing an Ethereum contract
+// call with the specified data as the input. The pending flag requests execution
+// against the pending block, not the stable head of the chain.
+func (b *ContractBackend) ContractCall(contract common.Address, data []byte, pending bool) ([]byte, error) {
+	// Convert the input args to the API spec
+	args := CallArgs{
+		To:   &contract,
+		Data: common.ToHex(data),
+	}
+	block := rpc.LatestBlockNumber
+	if pending {
+		block = rpc.PendingBlockNumber
+	}
+	// Execute the call and convert the output back to Go types
+	out, err := b.bcapi.Call(args, block)
+	if err == errNoCode {
+		err = bind.ErrNoCode
+	}
+	return common.FromHex(out), err
+}
+
+// PendingAccountNonce implements bind.ContractTransactor retrieving the current
+// pending nonce associated with an account.
+func (b *ContractBackend) PendingAccountNonce(account common.Address) (uint64, error) {
+	out, err := b.txapi.GetTransactionCount(account, rpc.PendingBlockNumber)
+	return out.Uint64(), err
+}
+
+// SuggestGasPrice implements bind.ContractTransactor retrieving the currently
+// suggested gas price to allow a timely execution of a transaction.
+func (b *ContractBackend) SuggestGasPrice() (*big.Int, error) {
+	return b.eapi.GasPrice(), nil
+}
+
+// EstimateGasLimit implements bind.ContractTransactor triing to estimate the gas
+// needed to execute a specific transaction based on the current pending state of
+// the backend blockchain. There is no guarantee that this is the true gas limit
+// requirement as other transactions may be added or removed by miners, but it
+// should provide a basis for setting a reasonable default.
+func (b *ContractBackend) EstimateGasLimit(sender common.Address, contract *common.Address, value *big.Int, data []byte) (*big.Int, error) {
+	out, err := b.bcapi.EstimateGas(CallArgs{
+		From:  sender,
+		To:    contract,
+		Value: *rpc.NewHexNumber(value),
+		Data:  common.ToHex(data),
+	})
+	if err == errNoCode {
+		err = bind.ErrNoCode
+	}
+	return out.BigInt(), err
+}
+
+// SendTransaction implements bind.ContractTransactor injects the transaction
+// into the pending pool for execution.
+func (b *ContractBackend) SendTransaction(tx *types.Transaction) error {
+	raw, _ := rlp.EncodeToBytes(tx)
+	_, err := b.txapi.SendRawTransaction(common.ToHex(raw))
+	return err
+}

node/node.go

@@ -311,7 +311,7 @@ func (n *Node) startIPC(apis []rpc.API) error {
 				glog.V(logger.Error).Infof("IPC accept failed: %v", err)
 				continue
 			}
-			go handler.ServeCodec(rpc.NewJSONCodec(conn), rpc.OptionMethodInvocation | rpc.OptionSubscriptions)
+			go handler.ServeCodec(rpc.NewJSONCodec(conn), rpc.OptionMethodInvocation|rpc.OptionSubscriptions)
 		}
 	}()
 	// All listeners booted successfully

node/service.go

@@ -68,7 +68,7 @@ type ServiceConstructor func(ctx *ServiceContext) (Service, error)
 //  - Restart logic is not required as the node will create a fresh instance
 //    every time a service is started.
 type Service interface {
-	// Protocol retrieves the P2P protocols the service wishes to start.
+	// Protocols retrieves the P2P protocols the service wishes to start.
 	Protocols() []p2p.Protocol
 
 	// APIs retrieves the list of RPC descriptors the service provides

release/contract.sol

+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// ReleaseOracle is an Ethereum contract to store the current and previous
+// versions of the go-ethereum implementation. Its goal is to allow Geth to
+// check for new releases automatically without the need to consult a central
+// repository.
+//
+// The contract takes a vote based approach on both assigning authorised signers
+// as well as signing off on new Geth releases.
+//
+// Note, when a signer is demoted, the currently pending release is auto-nuked.
+// The reason is to prevent suprises where a demotion actually tilts the votes
+// in favor of one voter party and pushing out a new release as a consequence of
+// a simple demotion.
+contract ReleaseOracle {
+  // Votes is an internal data structure to count votes on a specific proposal
+  struct Votes {
+    address[] pass; // List of signers voting to pass a proposal
+    address[] fail; // List of signers voting to fail a proposal
+  }
+
+  // Version is the version details of a particular Geth release
+  struct Version {
+    uint32  major;  // Major version component of the release
+    uint32  minor;  // Minor version component of the release
+    uint32  patch;  // Patch version component of the release
+    bytes20 commit; // Git SHA1 commit hash of the release
+
+    uint64  time;  // Timestamp of the release approval
+    Votes   votes; // Votes that passed this release
+  }
+
+  // Oracle authorization details
+  mapping(address => bool) authorised; // Set of accounts allowed to vote on updating the contract
+  address[]                voters;     // List of addresses currently accepted as signers
+
+  // Various proposals being voted on
+  mapping(address => Votes) authProps; // Currently running user authorization proposals
+  address[]                 authPend;  // List of addresses being voted on (map indexes)
+
+  Version   verProp;  // Currently proposed release being voted on
+  Version[] releases; // All the positively voted releases
+
+  // isSigner is a modifier to authorize contract transactions.
+  modifier isSigner() {
+    if (authorised[msg.sender]) {
+      _
+    }
+  }
+
+  // Constructor to assign the initial set of signers.
+  function ReleaseOracle(address[] signers) {
+    // If no signers were specified, assign the creator as the sole signer
+    if (signers.length == 0) {
+      authorised[msg.sender] = true;
+      voters.push(msg.sender);
+      return;
+    }
+    // Otherwise assign the individual signers one by one
+    for (uint i = 0; i < signers.length; i++) {
+      authorised[signers[i]] = true;
+      voters.push(signers[i]);
+    }
+  }
+
+  // signers is an accessor method to retrieve all te signers (public accessor
+  // generates an indexed one, not a retreive-all version).
+  function signers() constant returns(address[]) {
+    return voters;
+  }
+
+  // authProposals retrieves the list of addresses that authorization proposals
+  // are currently being voted on.
+  function authProposals() constant returns(address[]) {
+    return authPend;
+  }
+
+  // authVotes retrieves the current authorization votes for a particular user
+  // to promote him into the list of signers, or demote him from there.
+  function authVotes(address user) constant returns(address[] promote, address[] demote) {
+    return (authProps[user].pass, authProps[user].fail);
+  }
+
+  // currentVersion retrieves the semantic version, commit hash and release time
+  // of the currently votec active release.
+  function currentVersion() constant returns (uint32 major, uint32 minor, uint32 patch, bytes20 commit, uint time) {
+    if (releases.length == 0) {
+      return (0, 0, 0, 0, 0);
+    }
+    var release = releases[releases.length - 1];
+
+    return (release.major, release.minor, release.patch, release.commit, release.time);
+  }
+
+  // proposedVersion retrieves the semantic version, commit hash and the current
+  // votes for the next proposed release.
+  function proposedVersion() constant returns (uint32 major, uint32 minor, uint32 patch, bytes20 commit, address[] pass, address[] fail) {
+    return (verProp.major, verProp.minor, verProp.patch, verProp.commit, verProp.votes.pass, verProp.votes.fail);
+  }
+
+  // promote pitches in on a voting campaign to promote a new user to a signer
+  // position.
+  function promote(address user) {
+    updateSigner(user, true);
+  }
+
+  // demote pitches in on a voting campaign to demote an authorised user from
+  // its signer position.
+  function demote(address user) {
+    updateSigner(user, false);
+  }
+
+  // release votes for a particular version to be included as the next release.
+  function release(uint32 major, uint32 minor, uint32 patch, bytes20 commit) {
+    updateRelease(major, minor, patch, commit, true);
+  }
+
+  // nuke votes for the currently proposed version to not be included as the next
+  // release. Nuking doesn't require a specific version number for simplicity.
+  function nuke() {
+    updateRelease(0, 0, 0, 0, false);
+  }
+
+  // updateSigner marks a vote for changing the status of an Ethereum user, either
+  // for or against the user being an authorised signer.
+  function updateSigner(address user, bool authorize) internal isSigner {
+    // Gather the current votes and ensure we don't double vote
+    Votes votes = authProps[user];
+    for (uint i = 0; i < votes.pass.length; i++) {
+      if (votes.pass[i] == msg.sender) {
+        return;
+      }
+    }
+    for (i = 0; i < votes.fail.length; i++) {
+      if (votes.fail[i] == msg.sender) {
+        return;
+      }
+    }
+    // If no authorization proposal is open, add the user to the index for later lookups
+    if (votes.pass.length == 0 && votes.fail.length == 0) {
+      authPend.push(user);
+    }
+    // Cast the vote and return if the proposal cannot be resolved yet
+    if (authorize) {
+      votes.pass.push(msg.sender);
+      if (votes.pass.length <= voters.length / 2) {
+        return;
+      }
+    } else {
+      votes.fail.push(msg.sender);
+      if (votes.fail.length <= voters.length / 2) {
+        return;
+      }
+    }
+    // Proposal resolved in our favor, execute whatever we voted on
+    if (authorize && !authorised[user]) {
+      authorised[user] = true;
+      voters.push(user);
+    } else if (!authorize && authorised[user]) {
+      authorised[user] = false;
+
+      for (i = 0; i < voters.length; i++) {
+        if (voters[i] == user) {
+          voters[i] = voters[voters.length - 1];
+          voters.length--;
+
+          delete verProp; // Nuke any version proposal (no suprise releases!)
+          break;
+        }
+      }
+    }
+    // Finally delete the resolved proposal, index and garbage collect
+    delete authProps[user];
+
+    for (i = 0; i < authPend.length; i++) {
+      if (authPend[i] == user) {
+        authPend[i] = authPend[authPend.length - 1];
+        authPend.length--;
+        break;
+      }
+    }
+  }
+
+  // updateRelease votes for a particular version to be included as the next release,
+  // or for the currently proposed release to be nuked out.
+  function updateRelease(uint32 major, uint32 minor, uint32 patch, bytes20 commit, bool release) internal isSigner {
+    // Skip nuke votes if no proposal is pending
+    if (!release && verProp.votes.pass.length == 0) {
+      return;
+    }
+    // Mark a new release if no proposal is pending
+    if (verProp.votes.pass.length == 0) {
+      verProp.major  = major;
+      verProp.minor  = minor;
+      verProp.patch  = patch;
+      verProp.commit = commit;
+    }
+    // Make sure positive votes match the current proposal
+    if (release && (verProp.major != major || verProp.minor != minor || verProp.patch != patch || verProp.commit != commit)) {
+      return;
+    }
+    // Gather the current votes and ensure we don't double vote
+    Votes votes = verProp.votes;
+    for (uint i = 0; i < votes.pass.length; i++) {
+      if (votes.pass[i] == msg.sender) {
+        return;
+      }
+    }
+    for (i = 0; i < votes.fail.length; i++) {
+      if (votes.fail[i] == msg.sender) {
+        return;
+      }
+    }
+    // Cast the vote and return if the proposal cannot be resolved yet
+    if (release) {
+      votes.pass.push(msg.sender);
+      if (votes.pass.length <= voters.length / 2) {
+        return;
+      }
+    } else {
+      votes.fail.push(msg.sender);
+      if (votes.fail.length <= voters.length / 2) {
+        return;
+      }
+    }
+    // Proposal resolved in our favor, execute whatever we voted on
+    if (release) {
+      verProp.time = uint64(now);
+      releases.push(verProp);
+      delete verProp;
+    } else {
+      delete verProp;
+    }
+  }
+}

release/contract_test.go

+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package release
+
+import (
+	"crypto/ecdsa"
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/accounts/abi/bind/backends"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+// setupReleaseTest creates a blockchain simulator and deploys a version oracle
+// contract for testing.
+func setupReleaseTest(t *testing.T, prefund ...*ecdsa.PrivateKey) (*ecdsa.PrivateKey, *ReleaseOracle, *backends.SimulatedBackend) {
+	// Generate a new random account and a funded simulator
+	key, _ := crypto.GenerateKey()
+	auth := bind.NewKeyedTransactor(key)
+
+	accounts := []core.GenesisAccount{{Address: auth.From, Balance: big.NewInt(10000000000)}}
+	for _, key := range prefund {
+		accounts = append(accounts, core.GenesisAccount{Address: crypto.PubkeyToAddress(key.PublicKey), Balance: big.NewInt(10000000000)})
+	}
+	sim := backends.NewSimulatedBackend(accounts...)
+
+	// Deploy a version oracle contract, commit and return
+	_, _, oracle, err := DeployReleaseOracle(auth, sim, []common.Address{auth.From})
+	if err != nil {
+		t.Fatalf("Failed to deploy version contract: %v", err)
+	}
+	sim.Commit()
+
+	return key, oracle, sim
+}
+
+// Tests that the version contract can be deployed and the creator is assigned
+// the sole authorized signer.
+func TestContractCreation(t *testing.T) {
+	key, oracle, _ := setupReleaseTest(t)
+
+	owner := crypto.PubkeyToAddress(key.PublicKey)
+	signers, err := oracle.Signers(nil)
+	if err != nil {
+		t.Fatalf("Failed to retrieve list of signers: %v", err)
+	}
+	if len(signers) != 1 || signers[0] != owner {
+		t.Fatalf("Initial signer mismatch: have %v, want %v", signers, owner)
+	}
+}
+
+// Tests that subsequent signers can be promoted, each requiring half plus one
+// votes for it to pass through.
+func TestSignerPromotion(t *testing.T) {
+	// Prefund a few accounts to authorize with and create the oracle
+	keys := make([]*ecdsa.PrivateKey, 5)
+	for i := 0; i < len(keys); i++ {
+		keys[i], _ = crypto.GenerateKey()
+	}
+	key, oracle, sim := setupReleaseTest(t, keys...)
+
+	// Gradually promote the keys, until all are authorized
+	keys = append([]*ecdsa.PrivateKey{key}, keys...)
+	for i := 1; i < len(keys); i++ {
+		// Check that no votes are accepted from the not yet authed user
+		if _, err := oracle.Promote(bind.NewKeyedTransactor(keys[i]), common.Address{}); err != nil {
+			t.Fatalf("Iter #%d: failed invalid promotion attempt: %v", i, err)
+		}
+		sim.Commit()
+
+		pend, err := oracle.AuthProposals(nil)
+		if err != nil {
+			t.Fatalf("Iter #%d: failed to retrieve active proposals: %v", i, err)
+		}
+		if len(pend) != 0 {
+			t.Fatalf("Iter #%d: proposal count mismatch: have %d, want 0", i, len(pend))
+		}
+		// Promote with half - 1 voters and check that the user's not yet authorized
+		for j := 0; j < i/2; j++ {
+			if _, err = oracle.Promote(bind.NewKeyedTransactor(keys[j]), crypto.PubkeyToAddress(keys[i].PublicKey)); err != nil {
+				t.Fatalf("Iter #%d: failed valid promotion attempt: %v", i, err)
+			}
+		}
+		sim.Commit()
+
+		signers, err := oracle.Signers(nil)
+		if err != nil {
+			t.Fatalf("Iter #%d: failed to retrieve list of signers: %v", i, err)
+		}
+		if len(signers) != i {
+			t.Fatalf("Iter #%d: signer count mismatch: have %v, want %v", i, len(signers), i)
+		}
+		// Promote with the last one needed to pass the promotion
+		if _, err = oracle.Promote(bind.NewKeyedTransactor(keys[i/2]), crypto.PubkeyToAddress(keys[i].PublicKey)); err != nil {
+			t.Fatalf("Iter #%d: failed valid promotion completion attempt: %v", i, err)
+		}
+		sim.Commit()
+
+		signers, err = oracle.Signers(nil)
+		if err != nil {
+			t.Fatalf("Iter #%d: failed to retrieve list of signers: %v", i, err)
+		}
+		if len(signers) != i+1 {
+			t.Fatalf("Iter #%d: signer count mismatch: have %v, want %v", i, len(signers), i+1)
+		}
+	}
+}
+
+// Tests that subsequent signers can be demoted, each requiring half plus one
+// votes for it to pass through.
+func TestSignerDemotion(t *testing.T) {
+	// Prefund a few accounts to authorize with and create the oracle
+	keys := make([]*ecdsa.PrivateKey, 5)
+	for i := 0; i < len(keys); i++ {
+		keys[i], _ = crypto.GenerateKey()
+	}
+	key, oracle, sim := setupReleaseTest(t, keys...)
+
+	// Authorize all the keys as valid signers and verify cardinality
+	keys = append([]*ecdsa.PrivateKey{key}, keys...)
+	for i := 1; i < len(keys); i++ {
+		for j := 0; j <= i/2; j++ {
+			if _, err := oracle.Promote(bind.NewKeyedTransactor(keys[j]), crypto.PubkeyToAddress(keys[i].PublicKey)); err != nil {
+				t.Fatalf("Iter #%d: failed valid promotion attempt: %v", i, err)
+			}
+		}
+		sim.Commit()
+	}
+	signers, err := oracle.Signers(nil)
+	if err != nil {
+		t.Fatalf("Failed to retrieve list of signers: %v", err)
+	}
+	if len(signers) != len(keys) {
+		t.Fatalf("Signer count mismatch: have %v, want %v", len(signers), len(keys))
+	}
+	// Gradually demote users until we run out of signers
+	for i := len(keys) - 1; i >= 0; i-- {
+		// Demote with half - 1 voters and check that the user's not yet dropped
+		for j := 0; j < (i+1)/2; j++ {
+			if _, err = oracle.Demote(bind.NewKeyedTransactor(keys[j]), crypto.PubkeyToAddress(keys[i].PublicKey)); err != nil {
+				t.Fatalf("Iter #%d: failed valid demotion attempt: %v", len(keys)-i, err)
+			}
+		}
+		sim.Commit()
+
+		signers, err := oracle.Signers(nil)
+		if err != nil {
+			t.Fatalf("Iter #%d: failed to retrieve list of signers: %v", len(keys)-i, err)
+		}
+		if len(signers) != i+1 {
+			t.Fatalf("Iter #%d: signer count mismatch: have %v, want %v", len(keys)-i, len(signers), i+1)
+		}
+		// Demote with the last one needed to pass the demotion
+		if _, err = oracle.Demote(bind.NewKeyedTransactor(keys[(i+1)/2]), crypto.PubkeyToAddress(keys[i].PublicKey)); err != nil {
+			t.Fatalf("Iter #%d: failed valid demotion completion attempt: %v", i, err)
+		}
+		sim.Commit()
+
+		signers, err = oracle.Signers(nil)
+		if err != nil {
+			t.Fatalf("Iter #%d: failed to retrieve list of signers: %v", len(keys)-i, err)
+		}
+		if len(signers) != i {
+			t.Fatalf("Iter #%d: signer count mismatch: have %v, want %v", len(keys)-i, len(signers), i)
+		}
+		// Check that no votes are accepted from the already demoted users
+		if _, err = oracle.Promote(bind.NewKeyedTransactor(keys[i]), common.Address{}); err != nil {
+			t.Fatalf("Iter #%d: failed invalid promotion attempt: %v", i, err)
+		}
+		sim.Commit()
+
+		pend, err := oracle.AuthProposals(nil)
+		if err != nil {
+			t.Fatalf("Iter #%d: failed to retrieve active proposals: %v", i, err)
+		}
+		if len(pend) != 0 {
+			t.Fatalf("Iter #%d: proposal count mismatch: have %d, want 0", i, len(pend))
+		}
+	}
+}
+
+// Tests that new versions can be released, honouring both voting rights as well
+// as the minimum required vote count.
+func TestVersionRelease(t *testing.T) {
+	// Prefund a few accounts to authorize with and create the oracle
+	keys := make([]*ecdsa.PrivateKey, 5)
+	for i := 0; i < len(keys); i++ {
+		keys[i], _ = crypto.GenerateKey()
+	}
+	key, oracle, sim := setupReleaseTest(t, keys...)
+
+	// Track the "current release"
+	var (
+		verMajor  = uint32(0)
+		verMinor  = uint32(0)
+		verPatch  = uint32(0)
+		verCommit = [20]byte{}
+	)
+	// Gradually push releases, always requiring more signers than previously
+	keys = append([]*ecdsa.PrivateKey{key}, keys...)
+	for i := 1; i < len(keys); i++ {
+		// Check that no votes are accepted from the not yet authed user
+		if _, err := oracle.Release(bind.NewKeyedTransactor(keys[i]), 0, 0, 0, [20]byte{0}); err != nil {
+			t.Fatalf("Iter #%d: failed invalid release attempt: %v", i, err)
+		}
+		sim.Commit()
+
+		prop, err := oracle.ProposedVersion(nil)
+		if err != nil {
+			t.Fatalf("Iter #%d: failed to retrieve active proposal: %v", i, err)
+		}
+		if len(prop.Pass) != 0 {
+			t.Fatalf("Iter #%d: proposal vote count mismatch: have %d, want 0", i, len(prop.Pass))
+		}
+		// Authorize the user to make releases
+		for j := 0; j <= i/2; j++ {
+			if _, err = oracle.Promote(bind.NewKeyedTransactor(keys[j]), crypto.PubkeyToAddress(keys[i].PublicKey)); err != nil {
+				t.Fatalf("Iter #%d: failed valid promotion attempt: %v", i, err)
+			}
+		}
+		sim.Commit()
+
+		// Propose release with half voters and check that the release does not yet go through
+		for j := 0; j < (i+1)/2; j++ {
+			if _, err = oracle.Release(bind.NewKeyedTransactor(keys[j]), uint32(i), uint32(i+1), uint32(i+2), [20]byte{byte(i + 3)}); err != nil {
+				t.Fatalf("Iter #%d: failed valid release attempt: %v", i, err)
+			}
+		}
+		sim.Commit()
+
+		ver, err := oracle.CurrentVersion(nil)
+		if err != nil {
+			t.Fatalf("Iter #%d: failed to retrieve current version: %v", i, err)
+		}
+		if ver.Major != verMajor || ver.Minor != verMinor || ver.Patch != verPatch || ver.Commit != verCommit {
+			t.Fatalf("Iter #%d: version mismatch: have %d.%d.%d-%x, want %d.%d.%d-%x", i, ver.Major, ver.Minor, ver.Patch, ver.Commit, verMajor, verMinor, verPatch, verCommit)
+		}
+
+		// Pass the release and check that it became the next version
+		verMajor, verMinor, verPatch, verCommit = uint32(i), uint32(i+1), uint32(i+2), [20]byte{byte(i + 3)}
+		if _, err = oracle.Release(bind.NewKeyedTransactor(keys[(i+1)/2]), uint32(i), uint32(i+1), uint32(i+2), [20]byte{byte(i + 3)}); err != nil {
+			t.Fatalf("Iter #%d: failed valid release completion attempt: %v", i, err)
+		}
+		sim.Commit()
+
+		ver, err = oracle.CurrentVersion(nil)
+		if err != nil {
+			t.Fatalf("Iter #%d: failed to retrieve current version: %v", i, err)
+		}
+		if ver.Major != verMajor || ver.Minor != verMinor || ver.Patch != verPatch || ver.Commit != verCommit {
+			t.Fatalf("Iter #%d: version mismatch: have %d.%d.%d-%x, want %d.%d.%d-%x", i, ver.Major, ver.Minor, ver.Patch, ver.Commit, verMajor, verMinor, verPatch, verCommit)
+		}
+	}
+}
+
+// Tests that proposed versions can be nuked out of existence.
+func TestVersionNuking(t *testing.T) {
+	// Prefund a few accounts to authorize with and create the oracle
+	keys := make([]*ecdsa.PrivateKey, 9)
+	for i := 0; i < len(keys); i++ {
+		keys[i], _ = crypto.GenerateKey()
+	}
+	key, oracle, sim := setupReleaseTest(t, keys...)
+
+	// Authorize all the keys as valid signers
+	keys = append([]*ecdsa.PrivateKey{key}, keys...)
+	for i := 1; i < len(keys); i++ {
+		for j := 0; j <= i/2; j++ {
+			if _, err := oracle.Promote(bind.NewKeyedTransactor(keys[j]), crypto.PubkeyToAddress(keys[i].PublicKey)); err != nil {
+				t.Fatalf("Iter #%d: failed valid promotion attempt: %v", i, err)
+			}
+		}
+		sim.Commit()
+	}
+	// Propose releases with more and more keys, always retaining enough users to nuke the proposals
+	for i := 1; i < (len(keys)+1)/2; i++ {
+		// Propose release with an initial set of signers
+		for j := 0; j < i; j++ {
+			if _, err := oracle.Release(bind.NewKeyedTransactor(keys[j]), uint32(i), uint32(i+1), uint32(i+2), [20]byte{byte(i + 3)}); err != nil {
+				t.Fatalf("Iter #%d: failed valid proposal attempt: %v", i, err)
+			}
+		}
+		sim.Commit()
+
+		prop, err := oracle.ProposedVersion(nil)
+		if err != nil {
+			t.Fatalf("Iter #%d: failed to retrieve active proposal: %v", i, err)
+		}
+		if len(prop.Pass) != i {
+			t.Fatalf("Iter #%d: proposal vote count mismatch: have %d, want %d", i, len(prop.Pass), i)
+		}
+		// Nuke the release with half+1 voters
+		for j := i; j <= i+(len(keys)+1)/2; j++ {
+			if _, err := oracle.Nuke(bind.NewKeyedTransactor(keys[j])); err != nil {
+				t.Fatalf("Iter #%d: failed valid nuke attempt: %v", i, err)
+			}
+		}
+		sim.Commit()
+
+		prop, err = oracle.ProposedVersion(nil)
+		if err != nil {
+			t.Fatalf("Iter #%d: failed to retrieve active proposal: %v", i, err)
+		}
+		if len(prop.Pass) != 0 || len(prop.Fail) != 0 {
+			t.Fatalf("Iter #%d: proposal vote count mismatch: have %d/%d pass/fail, want 0/0", i, len(prop.Pass), len(prop.Fail))
+		}
+	}
+}
+
+// Tests that demoting a signer will auto-nuke the currently pending release.
+func TestVersionAutoNuke(t *testing.T) {
+	// Prefund a few accounts to authorize with and create the oracle
+	keys := make([]*ecdsa.PrivateKey, 5)
+	for i := 0; i < len(keys); i++ {
+		keys[i], _ = crypto.GenerateKey()
+	}
+	key, oracle, sim := setupReleaseTest(t, keys...)
+
+	// Authorize all the keys as valid signers
+	keys = append([]*ecdsa.PrivateKey{key}, keys...)
+	for i := 1; i < len(keys); i++ {
+		for j := 0; j <= i/2; j++ {
+			if _, err := oracle.Promote(bind.NewKeyedTransactor(keys[j]), crypto.PubkeyToAddress(keys[i].PublicKey)); err != nil {
+				t.Fatalf("Iter #%d: failed valid promotion attempt: %v", i, err)
+			}
+		}
+		sim.Commit()
+	}
+	// Make a release proposal and check it's existence
+	if _, err := oracle.Release(bind.NewKeyedTransactor(keys[0]), 1, 2, 3, [20]byte{4}); err != nil {
+		t.Fatalf("Failed valid proposal attempt: %v", err)
+	}
+	sim.Commit()
+
+	prop, err := oracle.ProposedVersion(nil)
+	if err != nil {
+		t.Fatalf("Failed to retrieve active proposal: %v", err)
+	}
+	if len(prop.Pass) != 1 {
+		t.Fatalf("Proposal vote count mismatch: have %d, want 1", len(prop.Pass))
+	}
+	// Demote a signer and check release proposal deletion
+	for i := 0; i <= len(keys)/2; i++ {
+		if _, err := oracle.Demote(bind.NewKeyedTransactor(keys[i]), crypto.PubkeyToAddress(keys[len(keys)-1].PublicKey)); err != nil {
+			t.Fatalf("Iter #%d: failed valid demotion attempt: %v", i, err)
+		}
+	}
+	sim.Commit()
+
+	prop, err = oracle.ProposedVersion(nil)
+	if err != nil {
+		t.Fatalf("Failed to retrieve active proposal: %v", err)
+	}
+	if len(prop.Pass) != 0 {
+		t.Fatalf("Proposal vote count mismatch: have %d, want 0", len(prop.Pass))
+	}
+}

release/generator.go

+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+//go:generate abigen --sol ./contract.sol --pkg release --out ./contract.go
+
+package release

release/release.go

+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package release contains the node service that tracks client releases.
+package release
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/eth"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+	"github.com/ethereum/go-ethereum/node"
+	"github.com/ethereum/go-ethereum/p2p"
+	"github.com/ethereum/go-ethereum/rpc"
+)
+
+// Interval to check for new releases
+const releaseRecheckInterval = time.Hour
+
+// Config contains the configurations of the release service.
+type Config struct {
+	Oracle common.Address // Ethereum address of the release oracle
+	Major  uint32         // Major version component of the release
+	Minor  uint32         // Minor version component of the release
+	Patch  uint32         // Patch version component of the release
+	Commit [20]byte       // Git SHA1 commit hash of the release
+}
+
+// ReleaseService is a node service that periodically checks the blockchain for
+// newly released versions of the client being run and issues a warning to the
+// user about it.
+type ReleaseService struct {
+	config Config          // Current version to check releases against
+	oracle *ReleaseOracle  // Native binding to the release oracle contract
+	quit   chan chan error // Quit channel to terminate the version checker
+}
+
+// NewReleaseService creates a new service to periodically check for new client
+// releases and notify the user of such.
+func NewReleaseService(ctx *node.ServiceContext, config Config) (node.Service, error) {
+	// Retrieve the Ethereum service dependency to access the blockchain
+	var ethereum *eth.Ethereum
+	if err := ctx.Service(&ethereum); err != nil {
+		return nil, err
+	}
+	// Construct the release service
+	contract, err := NewReleaseOracle(config.Oracle, eth.NewContractBackend(ethereum))
+	if err != nil {
+		return nil, err
+	}
+	return &ReleaseService{
+		config: config,
+		oracle: contract,
+		quit:   make(chan chan error),
+	}, nil
+}
+
+// Protocols returns an empty list of P2P protocols as the release service does
+// not have a networking component.
+func (r *ReleaseService) Protocols() []p2p.Protocol { return nil }
+
+// APIs returns an empty list of RPC descriptors as the release service does not
+// expose any functioanlity to the outside world.
+func (r *ReleaseService) APIs() []rpc.API { return nil }
+
+// Start spawns the periodic version checker goroutine
+func (r *ReleaseService) Start(server *p2p.Server) error {
+	go r.checker()
+	return nil
+}
+
+// Stop terminates all goroutines belonging to the service, blocking until they
+// are all terminated.
+func (r *ReleaseService) Stop() error {
+	errc := make(chan error)
+	r.quit <- errc
+	return <-errc
+}
+
+// checker runs indefinitely in the background, periodically checking for new
+// client releases.
+func (r *ReleaseService) checker() {
+	// Set up the timers to periodically check for releases
+	timer := time.NewTimer(0) // Immediately fire a version check
+	defer timer.Stop()
+
+	for {
+		select {
+		// If the time arrived, check for a new release
+		case <-timer.C:
+			// Rechedule the timer before continuing
+			timer.Reset(releaseRecheckInterval)
+
+			// Retrieve the current version, and handle missing contracts gracefully
+			version, err := r.oracle.CurrentVersion(nil)
+			if err != nil {
+				if err == bind.ErrNoCode {
+					glog.V(logger.Debug).Infof("Release oracle not found at %x", r.config.Oracle)
+					continue
+				}
+				glog.V(logger.Error).Infof("Failed to retrieve current release: %v", err)
+				continue
+			}
+			// Version was successfully retrieved, notify if newer than ours
+			if version.Major > r.config.Major ||
+				(version.Major == r.config.Major && version.Minor > r.config.Minor) ||
+				(version.Major == r.config.Major && version.Minor == r.config.Minor && version.Patch > r.config.Patch) {
+
+				warning := fmt.Sprintf("Client v%d.%d.%d-%x seems older than the latest upstream release v%d.%d.%d-%x",
+					r.config.Major, r.config.Minor, r.config.Patch, r.config.Commit[:4], version.Major, version.Minor, version.Patch, version.Commit[:4])
+				howtofix := fmt.Sprintf("Please check https://github.com/ethereum/go-ethereum/releases for new releases")
+				separator := strings.Repeat("-", len(warning))
+
+				glog.V(logger.Warn).Info(separator)
+				glog.V(logger.Warn).Info(warning)
+				glog.V(logger.Warn).Info(howtofix)
+				glog.V(logger.Warn).Info(separator)
+			} else {
+				glog.V(logger.Debug).Infof("Client v%d.%d.%d-%x seems up to date with upstream v%d.%d.%d-%x",
+					r.config.Major, r.config.Minor, r.config.Patch, r.config.Commit[:4], version.Major, version.Minor, version.Patch, version.Commit[:4])
+			}
+
+		// If termination was requested, return
+		case errc := <-r.quit:
+			errc <- nil
+			return
+		}
+	}
+}